1, 3-dioxolane polymers



Patented June 21, 19 49 UNITED STATES PATENT OFFICE ramoxomnn POLYMERSWilliam F. Gresham, Wilmington, Del., assignor to E. I. du Pont deNemours & Company, Wilmington, Del., a corporation of Delaware NoDrawing. Application August 4, 1945, Serial No. 609,037

. 8 Claims.

This invention relates to a process for the preparation of organicpolymeric compounds and more particularly to their preparation from 1,3-dioxolane and linear acetals. It likewise relates to the resultingpolymers. This application is a continuation-in-part of U. S. Serial No.424,292, filed December 24, 1941, and patented August 14, 1945, as U. S.Patent 2,382,874.

The present invention provides new reaction products obtainablefrom thereaction of 1,3-dioxolane with other organic compounds. Another Objectof the invention is to provide new compositions of matter from1,3-dioxolane or its substitution products and linear acetals. Yetanother object is to provide a process for the interaction of1,3-dioxolane and its substitution products with acetals under acidconditions. Another object is to provide reaction conditions andcatalysts for such reactions, whereby valuable products are obtainable.Other objects and advantages of the invention will hereinafter appear.

Valuable products are obtained in accord with the invention by reacting1,3-dioxolane, substituted 1,3-dioxolane, or reactants which form thesecompounds with linear acetals including the formals, e. g.

Dimethyl formaldehyde acetal Diethyl formaldehyde acetal Methyl ethylformaldehyde acetal Dipropyl formaldehyde acetal Methyl propylformaldehyde acetal Ethyl propyl formaldehyde acctal Dibutylformaldehyde acetal Methyl butyl formaldehyde acetal Ethyl butylformaldehyde acetal Propyl butyl formaldehyde acetal Dibenzylformaldehyde acetal Dinaphthyl formaldehyde acetal and the higherformals in which R1 and R2 are similar or dissimilar alkyl, aryl,aralkyl, cyclic or alicyclic groups and especially hydroxy alkylsubstitutions such as: compounds having the structural formulaRCH(O(CH2)1|OH)2, in which n is in which R1 and R2 are similar to theabove and Re is a substituted or unsubstituted alkyl group which willgive products similar to those described under the formals foracetaldehyde, propanal, butanal, and higher symmetrical andunsymmetrical aldehyde acetals. Substituted acetals may be used in lieuof or in the acetals, such as:

2,2-dimethoxypropane (CH3) :0 OCHs) 2 2,2-diethoxypropane, (CH3) 2C(OCzHs) z 2-methoxy-2-ethoxypropane,

(CH3) 2C(OCH3) OCzHs conjunction with The products of the invention areof relativelyhigh molecular weight and will hereinafter'be referred toas polymers, which term will include all products containing1,3-dioxolane (or substituted 1,3-dioxolane)- and 'acetal residues, thepolymer containing at least three residues, two of which are similar.For example, the polymers resulting from the reaction of 1,3-dioxolanewith methylal will contain atleast one 1,3-dioxolane resi due asCH2OCH2CH2O and at least one meth- 4 or a formal with ethylene glycol.

3 ylal residue as -OCH2O. The polymers of the invention are believed tobe primarily linear in form although cyclic polymers may be present. Theacetals may be reacted in accord with the procedural details more fullyparticularized hereinafter, with 1,3-dioxolane and its substitutionproducts. 1,3-dioxolane has the chemical formula w-lth numbering asshown:

CHa-O and may be obtained by reacting formaldehyde Products withsubstituents in the 2 position can be readily obtained by reaction ofketones or other aldehydes either aliphatic or aromatic with ethyleneglycol. Thus, by way of example, many compounds are obtained which maybe employed in accord with the invention, such as2-methyl-1,3-dioxo1ane, 2-ethyl-1,3-dioxolane,2,2-dimethyl-1,3-dioxolane, 2,2-diethyl-1,3-dioxolane,2-phenyl1,3-dioxolane, 2,2-methylphenyl-1,3-dioxolane,

and higher dioxolanes substituted in like manner I which may, forexample, be obtained from ethylene glycol and acetaldehyde, propanal,acetone, diethyl ketone, benzaldehyde, methyl phenyl ke-- tone, andhigher substituted aldehydes respectively. The invention likewisecontemplates the use of dioxolanes substituted in the 4 and/or5positions. These dioxolanes are obtained by the interaction ofsubstituted 1,2-glyco1s with aldehydes, for example, 1,2-propyleneglycol plus formaldehyde will give 4-methyl-1,3-dioxolane and similarlythe following dioxolanes can'be' readily prepared from formaldehyde andthe corresponding glycols:

4-ethyl-L3-dioxolane,

4-propyl-L3-dioxolane,

4,5-dimethyl-1,3-dioxolane In lieu of 1,3-dioxolane, reactants may beused which form 1,3-dioxolane and in such reactions there would bepresent the acetal to be reacted together with, for example,formaldehyde and ethylene glycol, or other reactants which will form1,3-dioxolane.

Valuable polymers are obtainable by the reaction of small amounts of1,3-dioxolane or its clerivatives with large amounts of the acetal, thatis, in the order of 1-100 and the reverse is also true. The greater theamount of 1,3-clioxolane present, the greater becomes the viscosity ofthe polymers until solids are eventually produced, while contrarywise,the greater the ratio of the acetal the less viscous will be theresulting polymer. There appears to be no limiting factor restrictingthe proportion of reactants.

The reaction between the 1,3-dioxolane and the acetal is effected attemperatures ranging between -80 and 300 and preferably between 0 and150 C. Atmospheric, subor superatmospheric pressures may be used and, ifthe last, pressure may range between 1 and 1000 atmospheres or higher.Normally excellent results are obtained at or about atmosphericvpressure. If desired, the temperature of the reaction, especially whenpolymerization is carried out at the boiling point of the reactionmixture, may be controlled by varying the pressure on the boilingreactants.

It has been found advantageous to effect the reaction in the presence ofan acid catalyst, such, for example, as sulfuric acid, phosphoric acid:the halogen acids, such as hydrochloric acid, hydrofluoric acid (aloneor with BFz) boron fluoride (including its complexes with water, acids,esters, alcohols, and the like), paratoluene sulfgn ic acid, camphorsulfonic acid, and other acid catafysts of this general nature.Friedel-Crafts type catalysts other than BF's may be used, such asAlCla. AlBra, FeCla, and so forth, as well as inorganic acids generallyand their salts such as sodium acid sulfate, sodium acid phosphate, andso forth.

The catalyst may be supported or not on inert supports such as charcoal,silica gel (which alone is a catalyst for the reaction), kieselguhr, andso forth. Concentrations of BFs, H2804 and similarly strong catalystsmay be extremely low; less than 0.1%, and amounts down to as low as0.001% of the strong acid catalyst have been found sufflcient to givepolymers although high concentrations of the catalyst even equal to orgreater than the weight of the dioxolane are likewise satisfactory.

The reaction is preferably continued approximately to equilibrium inorder to obtain the above defined polymeric organic compounds. Thereaction may then be stopped by destroying the cata lyst. This may bedone by removing it (in the case of silica gel, kieselguhr, and thelike) or by treating the reaction mixture with an inorganic base, suchas ammonia, alkali metal, and alkaline earth metal hydroxides,carbonates, alkoxides, and so forth or an organic base, such aspyridine, dimethylamine, and the like. These bases are added insufficient amounts to neutralize the catalyst when acid catalysts areused, and the unconverted reactants may be removed by distillation underreduced pressure. As soon as the catalyst has been neutralized, thereaction ceases.

The neutralized catalyst may be filtered oif and the polymerized productwhich remains treated for the recovery of the polymers.

In the reaction of the dioxolanes with the acetals and more especiallywhen the higher molecular weight products are being prepared thereusually will be found in the reaction mixture along with the polymerunreacted dioxolane and the acetal together with by-products andpolymers which it is not desired to produce. It is possible to inhibitthe formation of the undesired products by carrying out the process inan intermittent or continuous manner whereby the desired polymer iswithdrawn from the reaction zone and the undesirable products, afterbeing separated therefrom, are returned to the reaction zone. By thismeans it is possible to obtain high yields'of the desired polymer.

In addition to being instrumental in stopping the reaction at thedesired point, the neutralization of the catalyst tends to stabilize thepolymers. It follows, therefore, that for high temperature uses no acidshould be present in the polymers. They should preferably be neutralor-on the alkaline side.

Examples will now be given illustrating embodiments of the invention butit will be understood that it will not be limited by the detailsthereof. Parts are by weight unless otherwise indicated.

Example 1.-A reaction mixture consisting of 222 parts of 1,3-dioxolane,684 parts of methylal and 4.5 parts of sulfuric acid was heatedv under areturn condenser supplied with a calcium chloride drying tube for 6.5hours. Subsequent to neutralization of the catalyst by addition of 4.04.parts of sodium hydroxide dissolved in 10 parts of water to the cooledreaction mixture, the product was fractionally distilled, in the finalstages under reduced pressure. 64.5 parts of di(methoxymethoxy) ethane(CHQOCHxOCHzCHZOCI-IZOCI-h) B. P. 83 C./29 mm., was obtained. Physicaland chemical constants of this compound are: hy-'(ClCHzCHzOCHzOCECI-IzOUHzOCI-IzCHzCI) B. P. 128 C./28 mm. Unconvertedreactants and undesirable by-products were recycled. This gave anadditional 84 parts of diUS-chloroethoxymethoxy) ethane.

Example 3.--A reaction mixture of 1'73 parts (1 mole) ofdHB-chloroethyl) formal, 740 parts moles) of 1,3-dioxo1ane and 4 parts(0.04 mole) sulfuric acid was heated for five hours on a steam' bath,ammonia was introduced to substantial neutralization and then 3.4 partsof sodium hydroxide added in 10 parts of water; 233.5 parts of theunchanged 1,3-dioxolane and lower boilers being removed by distillation.Benzene was added to the residue, the mixture filtered, ben'zene removedby distillation and 669.6 parts of a polymer obtained. It is an almostcolorless viscous liquid with a solubility of slightly less than 10% inwater which contains the group ClCHzCEOCHzOCHzCHzOCI-IzOCHzCHzOCHa- Themolecular weight as determined by the boiling point method was between760 and 770.

Example 4.A reaction mixture of 328 parts (2 moles) ofdiqs-methoxyethyl) formal, 444 parts (6 moles) of 1,3-dioxolane and 3.5parts (0.034 mole) sulfuric acid was heated on a steam bath for 5 hours.The sulfuric acid was neutralized with ammonia followed by 3.1 parts ofsodium hydroxide and 10 parts of water. The lower boiling substanceswere distilled off at a temperature at about 100 C. and a pressure of 1mm. 187.5 parts. The solid salts were then filtered oil. The undistilledliquid consisting of 556.8 parts of a polymer, is a very lightly coloredmobile liquid miscible with water which contains the groupCH'iOCHaCHrOCHaOCHsC'H:

' OCH2OCH2CH2OCH2O- This liquid on analysis gave a molecular weightbetween 375 and 377 as determined by the boiling point method.

The products described are suitable for insecticidal uses, as carriersfor contact sprays such as nicotine solutions, the products acting aswetting and penetrating agents. They may be used as absorbents forrefrigerants; as flotation agents, the xanthates and sulphides of thelower molecular weight products being employed in this capacity; asextractants for vegetable and animal oils; as ingredients in paint andvarnish removers; as solvents in pigment drying; as softening agents incork processing and as carbon removers for use in internal combustionengines.

I claim: I

1. A process for producing polymers having 1,3-dioxolane residues(OCH2OCH2CH2) and linear formal residues (0CH20) there being present atleast three of the residues. at least two of which are 1,3-dioxolaneresidues and at least containing the group one is a linear formalresidue, which consists in subjecting at least two moles of1,3-dioxolane per mole of a linear formal to polymerization by mixingtogether in the presence of an acid catalyst.

2. A process for producing polymers having 1,3-dioxolane residues(OH20CH2CHa-) and methylal residues (-OCH20) there being present atleast three of the residues, at least two of which are 1,3-dioxolaneresidues and at least one is a methylal residue, which consists insubjecting at least two moles of 1,3-dioxoiane per mole of the methylalto polymerization by g together in the presence of an acid catalyst.

3. The process of claim I conducted at temper atures between 80 and 300C. and under a pressure between 1 and 1000 atmospheres.

4. The process of claim 1 conducted with sul furic acid as the catalyst.

5. A process for the preparation oi a tJiaZ containing the structureclcmcmocrno which comprises reacting approximately one mole ofdi(,3-chloroethyl) formal with approximately 10 moles of 1,3-dioxolanein the presence of 0.04

mole of sulfuric acid, the mixture being heated for about five hours ona steam bath, neutralizing the catalyst with ammonia and-aqueous sodiumhydroxide, removing the unconverted 1,3-dioxolane by distillation andthereafter recovering the polymer.

6. A process for the preparation of a polymer CHsOCHaCHzOCHzOCHaCH:

which consists in heating on a steam bath for approximately five hours amixture containing approximately two moles of diQB-methoxyethyl) formal,approximately six moles of 1,3-dioxolane in the presence ofapproximately 0.034 moles of sulfuric acid, neutralizing the catalystfirst with ammonia and then with aqueous sodium hydroxide, separatingthe unreacted 1,3-dioxolano by distillation and recovering the polymer.

7. A process for producing polymers having 1,3-dioxolane residues andlinear acetal-residues (ORO-, in which R is an alkylene group) whichpolymer contains at least three of the residues. two of which areidentical, which consists in subjecting at least two moles of1,3-dioxolane and a linear acetai which contains the group -0RO in whichR is 'an allnvlene group to polymerization by mixing together in thepresence of an acid catalyst. 8. A polymer which contains the group010mm which has the molecular weight as determined by the boiling pointmethod between 760 and 770 and has been prepared by reacting one moi ofdi(betachloroethyl) formal with at least two mole of 1,3-dioxolane inthe presence of an acid catalyst.

WILLIAM 1". Gm

' REFERENCES orrEn The following references are of record in the UNITEDSTATES PATENTS Name

